A soldier stands guard in the river as hundreds of protesters are detained faced down on the riverbank near a Tak Bai police station in Narathiwat province, 1,200km (745 miles) south of Bangkok, in this October 25, 2004 file photo. Thailand has dropped charges against 92 Muslims involved in a 2004 protest in the rebellious far south that led to 78 Muslims dying in army custody, the Attorney General's office said on Friday.